Berlin 2008 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 35: Phase Transitions I

MM 35.4: Talk

Thursday, February 28, 2008, 11:00–11:15, H 0107

Dynamic observation of ac field induced twin boundary motion in bulk NiMnGa — •Ryan Yiu Wai Lai, Jeffrey McCord, Rudolf Schaefer, and Ludwig Schultz — Leibniz-Institute for Solid State and Materials Research, P.O.Box 270116, Dresden D-01171, Germany

A study of actuating performance in bulk NiMnGa magnetic shape memory single crystals at various frequencies is presented. A dynamic actuation experimental setup with the ability to apply mechanical stress and alternating magnetic field perpendicularly is developed in cooperation with time-resolved microscopy. Reversible twin boundary motion activated in the frequency range up to 600Hz is directly observed. The maximum field induced strain increases with actuation frequency. Strain hysteresis curves show a pronounced dependency on actuation frequency. The mechanism of the frequency response will be discussed in detail. Funding through the DFG priority program SPP1239 is gratefully acknowledged.